Typhoon victims are transported on farm tractors and a truck along a flooded portion of a highway in Zaragoza, Nueva Ecija in northern Philippines October 20, 2015, after the province was hit by Typhoon Koppu. Photo: Reuters/Erik De Castro

A typhoon that dumped heavy rains on the northern Philippines, killing 26 people as it flattened houses and destroyed crops, weakened on Wednesday before heading towards southern Japan.

Raging floodwaters and landslides in the main Philippine island of Luzon were responsible for most of the deaths, Romina Marasigan, a spokeswoman for the national disaster agency, told reporters.

More than 100,000 people are still in temporary shelters as Koppu destroyed more than 6.57 billion pesos ($141.63 million) worth of crops, infrastructure and homes.

"We were terrified and prayed as we stayed under a table for hours after strong winds blew away the roof and walls of our house," said one survivor, Andres Subang, 72, wiping away tears as he told of how his family made it through the disaster.

"I have experienced countless typhoons in my lifetime, but this was the worst. It left nothing, we have no food and no more livelihood."

Farm officials said flooding destroyed 5 percent of expected fourth-quarter production in the rice-producing provinces nationwide.

Authorities in the coastal town of Casiguran, where Koppu made landfall as a category 4 typhoon, are deploying heavy equipment to clear roads of uprooted trees, toppled electric posts and debris.

"When we went around the town, we saw the typhoon's destructive impact, there were so many houses destroyed," municipal official Nida Coralde told Reuters, adding that distribution of relief supplies had begun.

Strong winds reduced people's homes to matchwood, leaving them with nothing, said one survivor, as residents began work to repair homes.

Strong winds grounded military planes and helicopters on Tuesday, forcing the government to send in food, water and other relief materials by road. Some areas were still flooded, without power and communication links.